Acne is a common multi-factor pathology that attacks areas of the skin rich in sebaceous glands such as the face, shoulder area, arms and intertriginous areas. Acne is the most commonly occurring form of dermatosis. There are five pathogenic factors playing a determining role in the formation of acne: genetic predisposition; overproduction of sebum (seborrhea); androgens; follicular keratinization disorders (comedogenesis); and bacterial colonization and inflammatory factors. There are several forms of acne such as acne conglobata, keloid acne of the nape of the neck, acne medicamentosa, recurrent miliary acne, necrotic acne, neonatal acne, premenstrual acne, occupational acne, acne rosacea, senile acne, solar acne and common acne; the common factor of all being attack of the pilosebaceous follicles.
The various forms of acne described above can be treated with active agents. Such active agents include, without limitation, anti-seborrheic agents and anti-infectives, such as benzoyl peroxide and keratolytic agents including salicylic acid. Various compositions are used for cleansing the skin of acne patients. Preferably, such cleansers should not compromise the skin barrier or cause the skin to increase sebum production in reaction to drying or harsh ingredients.
Generally, anti-acne therapies may promote dry skin. However, such a tactic can produce skin barrier damage leading to an increased loss of water from the stratum corneum. An intact skin barrier is essential for the correct functioning of both the physical and chemical elements of the skin's protective mechanisms. Acne directly influences the skin barrier function via the inflammatory process and sebum overproduction. Excessive sebum production leads to imbalanced skin lipids and structural alterations in key barrier components such as fatty acids deficiency. Excessive sebum production also leads to depletion of cholesterol and ceramides, which, in turn, may lead to an increased TEWL (Trans Epidermal Water Loss). Skin barrier damage and increased TEWL can aggravate acne. Consequently, dermatologists recognize the value of moisturizers and cleansers as adjuncts to prescribed treatments.
Historically, sulfur has been used in several ways to promote skin health. The use of sulfur in a variety of dermatological products has been known for many years for treating acne. Dermatologists sometimes recommend topical sulfur ointments for treating dermatological disorders such as acne vulgaris, acne rosacea, mite infestations, seborrheic dermatitis, rosacea, eczema, and dandruff and other conditions. Sulfur has also been used topically to treat warts, pityriasis versicolor or skin discoloration, hair-follicle infections, and shingles. Sulfur appears to assist in shedding excessive skin and targeting bacteria on the skin. Patients usually apply sulfur products topically rather than consuming them orally. Topical forms of sulfur products are in the form of creams or ointments, cleansers, gels, lotions, and topical suspensions. However, as recognized in the art, there are several drawbacks associated with sulfur formulations.
First, sulfur may degrade into malodorous components, such as sulfanilamide. Chemical and physical stability of sulfur compositions has been difficult to achieve. Many sulfur compositions degrade, turn color, and become malodorous in a relatively short time, which is undesirable to consumers. It is desirable to have non-malodorous and aesthetically pleasing compositions.
Second, sulfur tends to irritate the skin and eyes. As levels of sulfur are increased in attempt to improve a sulfur product's efficacy, irritation also tends to increase, making sulfur less desirable for use on or near delicate skin and/or the eyes. For instance, users may experience side effects such as skin dryness, itching, swelling, and irritation while using sulfur to treat skin problems. Further, applying sulfur to broken, wounded, sunburned or otherwise irritated skin can worsen the irritation.
Sulfur exists at room temperatures primarily as rhombic crystals. Other forms of sulfur, such as monoclinic crystalline sulfur, or polymeric sulfur, are the normal primary forms which elemental sulfur assumes at certain higher temperature ranges. At room temperatures, these forms convert, or revert, to rhombic sulfur.
Certain attempts to decrease the irritancy and odor of sulfur include compounding sulfur with other sorptive materials such as gums, clays, silicates, etc. in order to promote stability of the sulfur. Sorptive materials, when applied topically to the skin, absorb irritants, such as sweat, sebum, oil, and dirt, from the skin. However, the stability provided by these sorptive materials is limited and often not conducive to cleanser compositions. Further, while some improvements have been made in mildness or odor reduction, additional improvements in mildness are desirable, particularly improvements in both mildness and the ability to maintain strong efficacy.